The present invention relates generally to surgical devices used during knee surgery for the reinstatement of the natural knee joint. More particularly, the invention relates to a sizing apparatus wherethrough an appropriate size femoral component can be located and, thereafter, attached to the femoral distal end.
For various reasons, the human knee fails at the tibial and femoral juncture causing great pain and suffering to the individual. To correct this problem, surgeons now replace all or part of the natural knee joint with artificial components. Typically, a total knee replacement requires an artificial tibial component placed on the distal end of the tibia and an artificial femoral component placed at the distal end of the femur.
Because each individual's femur and tibia are different in size and because the extent of the damage to the tibia and femur distal ends cannot accurately be determined until after the knee has been cut open by the surgeon, the size of the implant components cannot easily be determined prior to the operation. Accordingly, it is common practice to initiate the operation, open up the knee, fully evaluate the needs of the patient and, at that time, determine the size of the femoral and tibial components. In view of this practice, manufacturers of femoral and tibial components typically manufacture five to eight different size components and arrange for all of their different sizes to be available to the surgeon during the operation. Accordingly, the surgeon must make a decision during the operation as to which of the different size components would best accommodate the patient's knee.
In the case of sizing the femoral distal end and determining which of the femoral component sizes to use, the common practice has been to measure the anterior to posterior distance of the femur and, utilizing this measurement, to pick an appropriate size femoral component. A typical device used by surgeons for measuring the anterior to posterior femoral distal end distance is shown at FIG. 1. As shown, the device includes a block having attached posterior arms. The posterior arms are placed on the back/underside portion of the femur condyles. The block further includes a vertically extending threaded rod upon which there is slidingly received an anterior arm or stylus. A nut member is threadingly received on the rod for engaging the anterior arm and forcing the anterior arm against an area proximal the intercondylar notch and toward the posterior arms. As shown in FIG. 1, during an operation, the surgeon places the device on the distal femoral end, tightens the bolt member, and directly reads the correct femoral component size for use on the patient.
Unfortunately, the prior art sizing component only takes into consideration the anterior to posterior distance somewhere further back from the distal condyles and does not take into consideration the medial to lateral distance, making it more difficult for the surgeon to determine the best fitting femoral component. Accordingly, the surgeon may initially utilize a femoral component that is either one size too large or one size too small, thereby requiring the surgeon to further reshape the femoral distal end to fit the chosen component.
Accordingly, there is a need for a femoral sizing device that better aids a surgeon in determining the appropriate size of femoral component.